1.3GB Magneto Optical disk Philips 5.25" - 130mm, Rewritable, Formatted Your PURCHASE is for ONE Philips MO 1.3gb DISK. 5.25-inch 1.3gb (Philips) rewritable magneto optical disk.  This 1.3gigabyte MO Disk is manufactured to the same standards as all other 1.3GB MO Disk.  It is a suitable replacement for any other brand of 1.3GB 5.25" Magneto Optical Disk. The disk is 100% certified and formatted. Made in Germany